Internet outage or no outage? That is the question

Twitter users tweeted this afternoon about a "rather large Internet outage" that was affecting access to the site, but an Internet traffic expert said he didn't see any major problems today.

The Internet Traffic Report showed problems for a period of time today for some routers serving North America. Specifically, three routers in Canada were registering zero response time and 100 percent packet loss, as were one in Mexico, New Hampshire, Texas, and Wisconsin. Routers in Nevada and Iowa appeared to be having less severe problems.

Representatives of the Internet Traffic Report did not respond to an e-mail seeking comment, or immediately respond to a phone message left for someone in Arizona listed as the administrator via the Whois domain lookup later today.

Bill Woodcock, research director of the Packet Clearing House, told CNET that he was not aware of any major Internet performance problems today.

"I know that there was an outage on Level 3's network in Phoenix between noon and 1 p.m. [PT]," he said. "There was certainly no general widespread outage at that time."

Level 3 provided this statement tonight: "At approximately noon PT, Level 3 experienced an isolated network issue that resulted in temporary voice and IP traffic disruptions for customers in the Phoenix area for approximately one hour. The company acted quickly to resolve the issue and service is now restored for those customers."

Meanwhile, at about 3:30 p.m. PT, Twitter's Support account said it was investigating "site availability issues some folks are experiencing."

Widely retweeted was a post from the Twitter API account that said, "If you can't access Twitter right now, it might be due to a rather large internet outage," and included the Internet Traffic Report Web link. That post was later removed.

So what's going on?

It could be the ripple effects of a relatively small problem--one that gets retweeted so much it appears to be much bigger than it is.

We'll keep you posted as we hear more.

Separately, AT&T confirmed an outage that affected Internet access for U-verse customers in the San Francisco Bay Area last night.

"A system update inadvertently caused incoming Internet traffic for the San Francisco market to be blocked," an AT&T spokesperson said in an e-mail. "We quickly identified and corrected it, and everything was restored in about two hours."

Updated 9:11 p.m. PT with Level 3 statement and 5:26 p.m. PT with AT&T U-verse outage in the San Francisco area.